Semiconductor optoelectronic (OE) devices, such as lasers, light emitting diodes, modulators and detectors have been extensively investigated for many years. As a result, optoelectronic device technology is generally at a high level, especially for discrete devices. However, integration of optoelectronic devices remains challenging. Two aspects of optoelectronic device integration are especially noteworthy. The first aspect is that OE integration often entails the use of multiple material systems. For example, Si technology is often preferred for passive waveguides, and non-Si (e.g., Ge, III-V, II-VI etc.) technology is often employed for active OE devices. Integration of active OE devices with Si technology is especially desirable to provide integrated access to the capabilities of Si electronics. The second aspect is that making optical connections between devices is fundamentally more difficult than making electrical connections between devices. For example, there is no optical waveguide technology that provides remotely close to the connection flexibility provided by patterned metal layers in electronic IC technology.
Various partial solutions to OE integration are known. For example, it is known to integrate an OE device with a waveguide, where the waveguide and OE device are in the same material system. It is also known to couple OE devices to waveguides on a photonic integrated circuit, e.g., by using grating couplers, or by butt-coupling a discrete OE device to the photonic integrated circuit.
Some aspects of non-OE integration technology are also of interest. For example, in U.S. Pat. No. 7,354,840, Kempf considers the monolithic integration of an electronic region and an optical region on the same substrate by selective epitaxy. Electrical connections between the electronic region and optical region are considered. However, optical connections are not considered in this work, presumably because the devices in the electronic region (e.g., bipolar transistors, CMOS devices) don't need (and can't accept) optical connections.
Accordingly, it would be an advance in the art to provide improved integration of OE devices.